The present invention relates generally to agricultural machinery and, more particularly, to improvements to root vegetable harvesting machines. The term "root vegetable" is intended to include, inter alia, edible roots and tubers.
In root vegetable harvesting technology there is a distinction between single-stage and two-stage harvesting methods. In the single-stage harvesting method the root vegetables are topped, dug up, cleaned and, after possible intermediate binning, transferred to a transport vehicle. In the two-stage harvesting method only topping and digging, and sometimes also cleaning, are carried out in the first stage. The dug-up root vegetables are then deposited onto the field. Only in the second stage does a harvesting machine pick up the deposited root vegetables, possibly clean them further, and load them onto a transport vehicle.
The planting of root vegetables to be harvested in the fields is critical for the design of the root vegetable harvesting machines. For sowing the root vegetables, a technique is known which uses a working width of 3 m. In some countries this is the legal limit for roading the machines. Six rows of root vegetables are typically sown over the 3 m. width. In order to follow the course of the rows of root vegetables when harvesting, without suffering harvesting losses due to deviations from adjacent drill tracks, the root vegetable harvesting machines known today harvest 1, 2, 3 or 6 rows of the root vegetables. This ensures the capability of harvesting within a six-row drill track or planting path. So far as known, there is no technique for harvesting root vegetables in excess of six rows for either the single-stage or the two-stage harvesting method.
Apart from the difficulty of compensating for deviations of adjacent drill tracks, a further difficulty in harvesting more than six rows of root vegetables lies in the inability to reliably control the quantities of root vegetables and topped leaves produced. It is difficult to deposit a swathe between the wheels of the harvesting machine when harvesting more than six rows because the deposited leaves are pressed into the ground and can not be distributed sufficiently, and deposited root vegetables may be damaged by the wheels, causing unacceptable losses of crop material. Also, the space between the two front wheels is too narrow to convey the usual quantity of root vegetables produced from the topping and digging implement to the cleaning equipment in the single-stage method.
A further problem lies in guiding the topping and digging unit so that the leaves are reliably separated and each individual root vegetable is reliably unearthed when harvesting several rows continuously and close to the ground. In cases of uneven ground surfaces, the greater the number of rows which are harvested in a single operation, the greater the risk that individual rows will be poorly topped and/or unearthed.
It is an object of the present invention to provide a root vegetable harvesting machine which can harvest more than six rows of root vegetables.
Another object is to provide a root vegetable harvesting machine which overcomes one or more of the difficulties described above.